The present invention relates to rotary sprinklers and more particularly to a new and improved impact type sprinkler.
Impact type fluid sprinklers of the general type to which the present invention relates are known in the art and generally include a rotatable housing having a nozzle and a spring-loaded oscillating impact arm for intermittent impact with the body to impart an increment of rotation thereto. The impact arm is adapted for impingement by the discharge stream against an end portion thereof to rotate the arm away from the discharge stream while the spring acts to reverse the direction of rotation of the arm and causes it to impact against the body. The cycle is repeated to produce a forward drive of the sprinkler by discrete increments.
Correct operation of the sprinkler is dependent on the relationship between the force of the discharge stream on the arm, as primarily determined by water pressure or nozzle size, and the force of the spring which resists the rotational movement of the arm and urges it in a reverse direction. The spring is selected to limit arm rotation to a desired maximum deflection within a range designed for selected water pressures and nozzle sizes. If the force applied to the impact arm by the discharge stream exceeds the design capacity of the spring, over deflection of the arm will occur and cause erratic sprinkler rotation. In extreme situations, the rotational movement of the impact arm may become sufficiently large to completely override the spring, permitting the arm to impact against the back of the body, thereby actually causing reverse rotation of the sprinkler. Further, operation of the sprinkler outside of the range of water pressures and nozzle sizes for which the sprinkler was designed can result in an undesirable water distribution pattern over the area to be irrigated.
The present invention overcomes the foregoing deficiencies of conventional impulse type sprinklers and provides an impact type sprinkler which gives uniform water distribution through a wide range of water pressures and nozzle sizes.